Debris catcher

ABSTRACT

A debris catcher can include an anchor connected to the wellbore tubular and a filter fixed to the anchor. The filter is formed at least partially of a degradable material and positioned in a bore of the wellbore tubular. A subterranean fluid flowing through the wellbore tubular is filtered using the debris catcher. It is emphasized that this abstract is provided to comply with the rules requiring an abstract, which will allow a searcher or other reader to quickly ascertain the general subject matter of the technical disclosure.

BACKGROUND OF THE DISCLOSURE

1. Field of the Disclosure

This disclosure relates generally to oilfield downhole tools and more particularly to methods and devices for filtering subterranean fluids using a debris catcher.

2. Description of the Related Art

Wellbore operations such as drilling, wireline logging, completions, perforations and interventions are performed to produce oil and gas from underground reservoirs. Wellbores can extend thousands of feet underground to the underground reservoirs. Some of these operations leave materials in the wellbore. These downhole materials flow back to the surface and require filtering. In some aspects, the present disclosure is directed to methods and devices for filtering a well using a debris catcher that is degradable.

SUMMARY OF THE DISCLOSURE

In one aspect, the present disclosure provides a debris catcher for performing a downhole operation in a wellbore tubular. The debris catcher may include an anchor connected to the wellbore tubular. The debris catcher may also have a filter fixed to the anchor. The filter may be formed at least partially of a degradable material and positioned in a bore of the wellbore tubular.

In another aspect, the present disclosure provides a method for performing a downhole operation in a wellbore tubular. The method may include conveying a debris catcher formed at least partially of a degradable material into the wellbore tubular. The method may also include filtering a subterranean fluid flowing through the wellbore tubular using the debris catcher.

Illustrative examples of some features of the disclosure thus have been summarized rather broadly in order that the detailed description thereof that follows may be better understood, and in order that the contributions to the art may be appreciated. There are, of course, additional features of the disclosure that will be described hereinafter and which will form the subject of the claims appended hereto.

BRIEF DESCRIPTION OF THE DRAWINGS

For detailed understanding of the present disclosure, references should be made to the following detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings, in which like elements have been given like numerals and wherein:

FIG. 1 shows an exemplary debris catcher at different locations along a wellbore tubular according to the present disclosure;

FIG. 2 shows an exemplary debris catcher with perforations and a shock absorber according to the present disclosure;

FIGS. 3 and 3A show side and end views, respectively, of an exemplary filter with perforations and a slicing member according to the present disclosure;

FIG. 4A-C show detailed views of exemplary filters with a core with beads according to the present disclosure; and

FIG. 5 shows an exemplary conical tapered filter according to the present disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

The present disclosure relates to devices and methods for filtering downhole tool materials using a debris catcher. The debris catcher is installed into the production string below the wellhead or as part of the wellhead assembly. The debris catcher catches particles and pieces in the subterranean fluid, for example, degradable downhole materials that flow back during production. The debris catcher prevents the downhole materials from damaging any wellbore components, such as valves. Also, the debris catcher degrades and can be removed from the flowbore. Illustrative debris catchers are described below.

FIG. 1 shows one non-limiting embodiment of the debris catcher 9 for filtering downhole materials 80 entrained in downhole fluids flowing towards the surface equipment. The debris catcher 9 may be run in conjunction with other bottom hole assemblies inside a wellbore tubular 10 such as a casing, liner, tubing or other suitable tubular. A conveyance device (not shown) is used to deploy and retrieve the debris catcher 9 into the wellbore tubular 10. The debris catcher 9 may be set at different locations along the wellbore including the vertical section 9 a, curved section 9 b, and/or horizontal section 9 c. Or, the debris catcher 9 may be located at the wellhead or Christmas tree 14 portion of the wellbore tubular 10. The downhole material 80 may be fragments or portions of a frac plug, frac balls, slips of a completion or production tool 82, etc. In some instances, the downhole material 80 may be a degradable material.

In some embodiments, the well tool 9 may include an anchor 20 affixed to a filter 30. The anchor 20 is configured to set the filter 30 with respect to the wellbore tubular 10. The anchor 20 may include slips, a packer or a nipple profile that snaps into a profile. As discussed in greater detail below, some or all of the filter 30 may be formed of a degradable material.

FIG. 2 shows an exemplary filter 30 that filters unwanted particles from downhole fluids, such as fluid produced from a subterranean formation. The filter 30 can have a housing 32 that may be formed of a degradable material and includes flowpaths such as perforations 36. The housing 32 can have a cylindrical form in the shape of a hollow basket, and a nose 31 pointing towards a downhole direction, which would be into the fluid flowing to the surface. The wellhead 14 end of the wellbore tubular 10 is the uphole side of the wellbore and the opposite end of the wellbore tubular 10 is the downhole side of the wellbore. The axial length of the filter 30 may change depending on the size and amount of the downhole material 80, subterranean fluids, degradation time limits, and perforation design.

The perforations 36 may have a pattern, shape, and/or size that depend on the nature of the debris to be filtered from the fluid. The perforations 36 or other channels 38 may be sized to selectively admit only certain particles to pass through to the surface. For example, their size may be large enough to allow the passage of some harmless material to the well equipment and to allow enough fluid flow to the surface. However, large debris or other undesirable particles in the downhole fluid, which are larger than a predetermined size, are prevented from passing through the perforations 36. For example, the flowpaths are sufficiently small to reduce the likelihood that the particles will impact or get caught in a valve along the wellbore, or corrode or otherwise damage the wellbore. Regarding shape, perforations 36 may be circular, oval, slots, or slits, for instance. In addition, the perforations 36 may be in a wrapped-screen or other screen form.

In some embodiments, the perforation 36 are open prior to and during deployment. In other embodiments, the perforations 36 can be open or filled with a degradable material prior to deployment.

Herein, “degradable” means disintegrable, corrodible, decomposable, soluble, or at least partially formed of a material that can undergo an irreversible change in its structure. Examples of suitable materials and their methods of manufacture are given in United States Patent Publications No. 2013/0025849 (Richard and Doane) and 2014/0208842 (Miller et al.), and U.S. Pat. No. 8,783,365 (McCoy and Solfronk), which Patent Publications and patents are hereby incorporated by reference in their entirety. A structural degradation may be a change in phase, dimension or shape, density, material composition, volume, mass, etc. The degradation may also be a change in a material property; e.g., rigidity, porosity, permeability, etc. Also, the degradation occurs over an engineered time interval; i.e., a predetermined time interval that is not incidental. Illustrative time intervals include minutes (e.g., 5 to 55 minutes), hours (1 to 23 hours), or days (2 to 3 or more days). Also, the degradation happens at a specific time based on environmental and structural inputs, which may be human initiated and controlled. For the purposes of this disclosure, biodegradable materials are not considered degradable because such materials rely on uncontrolled interaction with microorganisms.

The degradable material can be high-strength and lightweight, and have fully-dense, sintered powder compacts formed from coated powder materials that include various lightweight particle cores and core materials having various single layer and multilayer nanoscale coatings. These powder compacts are made from coated metallic powders that include various electrochemically-active (e.g., having relatively higher standard oxidation potentials) lightweight, high-strength particle cores and core materials, such as electrochemically active metals, that are dispersed within a cellular nanomatrix formed from the various nanoscale metallic coating layers of metallic coating materials, and are particularly useful in borehole applications.

Suitable core materials include electrochemically active metals having a standard oxidation potential greater than or equal to that of Zn, including as Mg, Al, Mn or Zn or alloys or combinations thereof. For example, tertiary Mg—Al—X alloys may include, by weight, up to about 85% Mg, up to about 15% Al and up to about 5% X, where X is another material. In one embodiment, the material has a substantially uniform average thickness between dispersed particles of about 50 nanometers (nm) to about 5000 nm. In one embodiment, the coating layers are formed from Al, Ni, W or Al2O3, or combinations thereof. In one embodiment, the coating is a multi-layer coating, for example, comprising a first Al layer, a Al2O3 layer and a second Al layer. In some embodiments, the coating may have a thickness of about 25 nm to about 2500 nm. In addition, surface irregularities to increase a surface area of the filter 30, such as grooves, corrugations, depressions, etc. may be used.

As noted above, the degradation is initiated by exposing the degradable material to a stimulus. In embodiments, the filter 30 degrades in response to exposure to a fluid. Illustrative fluids include engineered fluids (e.g., frac fluid, acidizing fluid, acid, brine, water, drilling mud, etc.) and naturally occurring fluids (e.g., hydrocarbon oil, produced water, etc.). The fluid used for stimulus may be one or more liquids, one or more gases, or mixtures thereof. In other embodiments, the stimulus may be thermal energy from surrounding formation. Thus, the stimulus may be engineered and/or naturally occurring in the well or wellbore tubular 10 and formation.

The filter 30 may also include phenolics, polyvinyl alcohols, polyacrylamide, polyacrylic acids, rare earth elements, glasses (e.g. hollow glass microspheres), carbon, elastic material, or a combination of these materials or above sintered powder compact material. Elastic material herein includes elastomers and means that the filter 30 can flex.

In one method of operation, the conveyance device is used to deploy the debris catcher 9 at a specific target depth along the wellbore tubular 10. After fracturing is completed, the conveyance device pulls the well string up the wellbore. The debris catcher 9 is deployed and set at depth via the conveyance device. The anchor 20 is set. The well is allowed to flow up and produce subterranean fluids. The degradable material in the filter 30 degrades and opens the perforations 36 to flow. The filter 30 filters the subterranean fluid through the perforations 36. The downhole material 80 that cannot pass the filter 30 accumulates outside the housing 32 and degrades until it can pass through the perforations 36. After the process complete the debris catcher 9 may be retrieved.

The debris catcher 9 may be connected to the conveyance device through any suitable means. The conveyance device may be tubing, coiled tubing, drillpipe, wireline, slickline, electric line or a combination thereof. The conveyance device may also set the anchor 20.

It should be appreciated that the debris catcher 9 of the present disclosure is subject to various embodiments. In a non-limiting embodiment of the present disclosure, the perforations 36 may have any shape including various concave and convex shapes.

Another non-limiting embodiment of the present disclosure is shown in FIGS. 3 and 3A. The filter 30 may have beads in the perforations 36. The beads may have a uniform composition and/or size, or may be varied. For instance, the beads may have spherical or honeycomb shapes, or combinations of these. Also, some of the beads may include varying- and/or uniform-sized degradable material, and/or steel or other non-degradable alloys or composites.

Another non-limiting embodiment of the filter 30 using the degradable beads is described in reference to FIG. 4A-C. The filter 30 may have a housing 32 and a core 34 that is positioned inside the housing 32 as shown in FIG. 4A. The housing 32 may be composed of a non-degradable material such as steel or other metal alloys, or composites. The beads made of the degradable material form the core 34. The beads may have different compositions and/or sizes, as shown in detailed FIG. 4B, to degrade at different times or with respect to different stimuli. Also, the core 34 may have non-degradable beads. Alternatively, FIG. 4C shows the core 34 after the degradation process. Channels 38 may be formed in the core 34. The channels 38 may filter the downhole material 80.

In another embodiment, as referenced in FIG. 5, the filter 30 may have a conical shape or a shape with a hyperbolical cross-section. The nose 31 may face the downhole side. Alternatively, the filter 30 may be positioned as the nose 31 facing uphole. The housing 32 may have beads in uniform composition and geometry, or a medley as shown in detail in FIG. 4B.

In one non-limiting embodiment, the filter 30 may include a combination of structures and geometries as mentioned above and in FIGS. 2-5. For example, a downhole side of the filter 30 may have perforations 36 filled with the solid degradable material, and an uphole side of the filter 30 may have the housing 32 and the core 34 of beads.

In another embodiment, the debris catcher 9 may include a shock absorber 40 as shown in FIG. 2. The shock absorber 40 protects the debris catcher 9 from large pieces of downhole material 80 or downhole material 80 hitting at high speeds. The shock absorber 40 may have a collet-style-shape, or spring members. The shock absorber 40 may also have a slicing capability as shown in FIGS. 3 and 3A. An edge 42 of the shock absorber 40 with the slicing capability is sharp to separate the downhole material 80 into two or more pieces when the downhole material 80 is flowed toward uphole by the fluid. The shock absorber 40 of FIG. 3 can also work as a spring member, slowing down the downhole material 80 before the downhole material 80 hits the filter 30.

In another embodiment, multiple debris catchers 9 may be set at different depths, and each debris catcher 9 may have a different filtering capability. For instance, each filter 30 of the debris catcher 9 may degrade at different times, or may have different sized perforations 36 or filter 30 geometry, pattern, structure or composition. Some of the debris catchers 9 may have shock absorbers 40 with or without slicing capabilities. Therefore, downhole members 80 may be filtered at different filters 30 depending on the size and composition of the downhole member 80.

In a non-limiting method of operation, where the perforations 36 are already open, the filtering may begin once the anchor 20 is set.

As described above, the debris catcher 9 may be set at a single location and be degraded completely. Alternatively, a portion of the degradable material may be degraded at a first location; the debris catcher 9 may be set at a different location, and the filtering process may be repeated at that location. Or, different portions of the debris catcher 9 may be degraded at each location.

In another embodiment and method of operation, after a certain passage of time or based on a certain stimulus, the filter 30 of the debris catcher 9 may totally degrade. For example, the operator may pump fluid downhole to accelerate the degradation of the filter 30.

The debris catcher 9 according to the present disclosure can be used after various well treatment operations. The well treatment operations include well cleaning, hydraulic fracturing, acidizing, cementing, plugging, pin point tracer injection or other well stimulation or intervention operations. Stimulation operation is an operation that changes the characteristic of the formation or the fluid inside the formation.

The foregoing description is directed to particular embodiments of the present disclosure for the purpose of illustration and explanation. It will be apparent, however, to one skilled in the art that many modifications and changes to the embodiment set forth above or embodiments of different forms are possible without departing from the scope of the disclosure. It is intended that the following claims be interpreted to embrace all such modifications and changes. 

We claim:
 1. A debris catcher for performing a downhole operation in a wellbore tubular, comprising: an anchor connected to the wellbore tubular; and a filter fixed to the anchor, the filter being formed at least partially of a degradable material and positioned in a bore of the wellbore tubular.
 2. The apparatus of claim 1, wherein the filter comprises a hollow basket having perforations, wherein the degradable material is located in the perforations.
 3. The apparatus of claim 1, wherein the filter comprises a tube formed of degradable beads.
 4. The apparatus of claim 1, wherein the filter comprises a housing filled with degradable beads.
 5. The apparatus of claim 1, wherein the filter comprises non-degradable beads, and wherein the degradable material is located among the non-degradable beads.
 6. The apparatus of claim 1, wherein the degradable material comprises a plurality of components each with a varying rate of degradation in response to different stimuli.
 7. The apparatus of claim 1, wherein the filter comprises a cylindrical housing and a curved nose.
 8. The apparatus of claim 7, wherein the curved nose is directed towards a flow of fluid from the formation.
 9. The apparatus of claim 1, wherein the filter is conical tapered.
 10. The apparatus of claim 1, wherein the anchor comprises at least one of: (i) anchoring slips, (ii) a packer, and (iii) a nipple profile.
 11. The apparatus of claim 1, further comprises a shock absorber connected to the filter.
 12. The apparatus of claim 11, wherein the shock absorber includes a slicing member.
 13. The apparatus of claim 1, wherein the debris catcher is located at the surface termination of the wellbore tubular.
 14. A method for performing a downhole operation in a wellbore tubular, comprising: conveying a debris catcher formed at least partially of a degradable material into the wellbore tubular; filtering a subterranean fluid flowing through the wellbore tubular using the debris catcher.
 15. The method of claim 14, further comprising setting the debris catcher at a location one of: (i) a horizontal section of the wellbore tubular, (ii) a vertical section of the wellbore tubular, (iii) a curved section of the wellbore tubular, (iv) wellhead of the wellbore tubular, and (v) a Christmas tree of the wellbore tubular.
 16. The method of claim 14, further comprising retrieving the debris catcher.
 17. The method of claim 14, further comprising pumping a degrading fluid into the wellbore tubular to degrade the degradable material.
 18. The method of claim 14, further comprising mechanically separating a downhole member with a slicing member of the debris catcher. 